Electrical mixing system



July 7,1942.v J FLINT 2,289,186

' ELECTRICAL MIXING SYSTEM Filed July 27, 1940 6 sh ets-sheet 1 0| 602 W CONTROLTUBEBOX- v 1!, G03

ELEVATOR WAYTROL GOG luvs/v70? JAMES A. FLINT,

y 1942. J. A. FLl NT 2,289,186 v ELECTRICAL MIXING SYSTEM Filed July 27, 1940 6 Sheets-Sheet 2 #6 O ES kg 5 5 G. E. 57 CONTROL BOX //YVE/YTOR-' JAMES A. FLINT,

July 7, 1942. J. A. FLINT ELECTRICAL MIXING SYSTEM Filed .July 2'7, 1940 6Sheets-Sheet 3 XOD J NEIZOUUU ZUZMD MOPOZ /NVEN7'OE.' JAMES A. FLINT,

f Orv HTT'Y y 1942' J. A. FLINT 2,289,186

' ELECTRICAL MIXING SYSTEM Filed July 27, 1940 6 Sheets-Sheet 4 SAFETY SWITCH;

I 5G! (FAST) /NVE/YTOE 3 JAMES A. FLINT,

ATT Y WAYTROL con-reap. Box A' July 7, 1942. FLINT 2,289,186

ELECTRICAL MIXING SYSTEM Filed July 27, 1940 6 Sheets-Shet 5 [/Yl/E/YTOR JAMEs A. FLINT,

MA5TER MOTOR DRIVEN RHEO5TAT P 00 In Patented July 7, 1942 ELECTRICAL MIXING SYSTEM James A. Flint, Columbus, Ohio, assignor to The Traylor Vibrator Company, a corporation of Colorado Application July 27, 1940, Serial No. 347,896 11 Claims. (01. 198-37) This invention relates to a system for automatically and continuously feeding materials to a receiver, such as a crusher, conveyor or elevator, in which the materials delivered to said receiver are consistently maintained in a predetermined ratio.

An object of the invention is to provide a system of the above mentioned type in which the feed ratio of the various materials is maintained constant Within extremely accurate limits, and limits which are much more accurate than any heretofore realized.

A further object of the invention is to provide a system of the remote control type in which an operator at a central station will be constantly informed of the feed ratio of a plurality of feeders.

A further object of the invention is to provide means for feeding material at a rate which is always directly proportional to the speed of a continuous weighing mechanism which is operated at a variable speed.

A further object of the invention is to provide an interlocked pair of constant. weight feeders to require their operation in a certain sequence.

A further object of the invention is to provide an improved control and alarm system for a system of the above mentioned type.

Another object of the invention is to provide -a feeder system in which the load on the receiving device, such as a conveyor, elevator or crusher, is automatically maintained substantially constant at all times.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings:

Figs. 1, 2 and 3 go together to make up the complete system with Fig. 1 positioned at the left of Fig. 3, and Fig. 2 placed above Fig. 3;

Fig. 4 is a detail of a control tube box;

Fig. 5 shows the apparatus and connections inside the G. E. control box illustrated on Fig. 2 of the drawings;

Fig. 6 shows the apparatus and connections inside the Waytrol, control box A of Figs. 2 and 3 of the drawings which is the same construction as the Waytrol control box B of said Fig. 2 of the drawings;

Fig. 7 shows the internal construction of the master motor driven rheostat of Fig. 3 of the drawings; and

Figs. 8, 9, 10 and 11 are simplified cross the line diagrams of various parts of the system which will be evident by comparison between these figures and other figures of the drawings.

There has been an ever increasing demand for an extremely accurate but highly flexible system for delivering a plurality of materials to a conveyor, elevator or crusher which are thereby or thereafter mixed to form some composite material. For example, in the manufacture of Portland cement, it is extremely desirable to mix limestone and shale-prior to the forming of the clinker in a very accurate ratio, and it is desirable that this ratio be adjustable .with ease and accuracy and the ratio be maintained throughout a wide range of adjustment.

It is furthermore desirable that the feed rate of the total material be manually or automatically adjustable while maintaining the ratio of the two materials intact.

Also, in the manufacture of Portland cement, after the clinker has been formed a similar mixing of clinker and gypsum is desired with the same flexibility and accuracy. This is of course only one illustration of which many might be given, such as the mixing of the ingredients to make glass, and the mixing of various ores.

Referring particularly to Figs. 1, 2 and 3 of the accompanying drawings, and first to Fig. 1 thereof, it will be seen that I have provided an elevator or elevating type of conveyor 400 having an electrical motor 40l adapted to be controlled by a solenoid operated switch 402 which controls the delivery of power from power mains Ll, L2 and L3 through a disconnect switch 403. Purely as illustrative andby no means as restrictive,

. the power mains Ll, L2 and L3 may have a voltage of 440 volts. Material is delivered to the boot of the elevator 400 by a pair of weighing feeder devices 404 and 405 which generally follow the construction of the constant capacity may follow the structure of the constant capacity feeder as disclosed in the patent to E. V. Francis et al., No. 2,164,812, dated July 4, 1939.

The weighing feeder devices 404 and 405 are of similar construction, and so a brief description of one will suflice for both.

Said device 404 includes a hopper 406 which feeds a vibratory feeder" 401 which in turn feeds a weighing mechanism comprising a continuous belt 408 carried between a pair of pulleys 409 and 4H! mounted upon a tiltable frame provided with appropriate counterbalancing scale mechanism which may be adjusted but during normal operation is maintained fixed with the weight at a definite position on the control poise. The pulley 4i is driven through a speed reducing mechanism from a receiving motor I of the Selsyn type, the 3-phase rotor of which is connected over lines H2, H3 and 414 to the 3- phase rotor of the driving Selsyn motor 4 [5 (Fig.

The stators of the two Selsyn motors 4H and H5 are energized as hereinafter pointed out, but

as is well-known in a Selsyn system, the electrical connections betweenthe receiving motor 4| l and the driving motor 5 are such as to maintain them in synchronism once they are started in operation, thus providing what is in effect a positive electrical driving connection between the driving motor 5 and the receiving motor 4| I.

It may be stated that this specific type of driving connection. that is, the Selsyn type, has been found very satisfactory and is the preferred form to be employed in my invention, but other wen known drives which accomplish an equivalent result may be employed in place of the Selsyn type.

Associated with the weighing feeder device 405 is a'receiving Selsyn motor 8 which will be understood to be in relation to device 405 similar to that which motor 4 bears to device 404.

The rotor of Selsyn motor 8 is connected over lines 411, 8 and 4!! to the rotor of the driving Selsyn motor 420. The outputs from the two weighing feeder devices 404 and 405 are delivered to chutes 42! and 422, respectively, both of which feed into the boot of the elevator 400 as diagrammatically illustrated in Fig, 1 of the drawings. It may be stated that the apparatus disclosed in Fig. l of the drawings may or may not be located at a station which is removed from the control station at which control station all of the apparatus disclosed in Figs. 2 and 3 of the drawings will be concentrated. It is thus possible in the system of my invention to control the operation of a plurality of weighing feeder devices from a remote position and to know exactly the feed ratios of these two devices within very accurate limits. To know this ratio the counterpoise weights of the two weighing feeder devices 404 and 405 are preferably, but not necessarily, set at the same position so that both of the pivoted endless belt conveyors will carry the same constant amount of material at all times which is automatically controlled as hereinafter pointed out more completely; However, the counterpoise weights may have different settings on the two machines, in which case the feed ratio will be the ratio of the counter-poise reading times the speed of the two machines. The ratio of these feeds from the two weighing feeder devices 404 and 405 I have found to be controlled with extreme accuracy over a range from practically no load to maximum load by varying the speeds of travel of the two endless belts of said devices 404 and 405 (that of the former being seen at 408) and then comparing these two speeds. To this end the driving Selsyn motors H5 and 420 are provided with speed indicating and total travel recording tachometer odometers 423 and 424 which are of course visible at the operator's station, and by comparing the speeds of the two the feed ratio of the feed from weighin feeder devices 404 and 405 is very accurately indicated over the entir range of operation thereof.

The two driving Selsyn motors H5 and 420 are driven from a variable speed induction motor 425 or any other type of variable speed motor, the speed of which is adjusted by a master motor driven rhecstat 426 illustrated in detail as to the electrical circuits in Fig. 7 of the drawings which is hereinafter described completely.

As is well known, the speed of an induction motor may be adjusted by varying the amount of resistance in circuit with the wound rotor. The induction motor 425 drives the two driving Selsyn motors H5 and 420 through a variable speed Selsyn drive mechanism 421 which may take the form of any well known form of variable speed drive in which driving Selsyn motor 420 is driven directly from motor 425 and driving Selsyn motor 5 is driven through the variable speed Selsyn drive 421 and through a magnetic clutch 428 by which driving Selsyn motor 4I5 may be disconnected in case it is desired to operate only one of the weighing feeder mechanisms 404 and 405.

In this connection it may be pointed out that whenever induction motor 425 is operated, the weighing feeder device 405 is also operated but the weighing feeder device 404 may be shut down and this makes possible feeding of material from one of the weighing feeder devices 404 and 405, namely, device 405 independently of the operation of the other.

It is of course evident that the variable speed Selsyn drive 421 will determine the feed ratio of the two weighing feeder devices 404 and 405 and this ratio may be adjusted by adjusting said variable speed Selsyn drive 421. The total feed of the two weighing feeder devices 404 and 405 may be adjusted while maintaining the feed ratio absolutely constant by adjusting the speed of motor 425. In prior known devices where attempts have been made to accomplish this result, there has inherently been an introduction of errors because of the fact that the Waytrols being adjusted did not have exactly the same characteristics or where attempts were made to control two vibratory feeders by increasing the current in the two simultaneously their characteristics curves are such that the feed ratio of the two is not maintained over any appreciable range of operation. With my system, however, since the only thing that.can possibly change the feed ratio of the two weight feeder devices 405 and 405 is the adjustment of the variable speed Selsyn drive 421, assuming of course that both devices 404 and 405 are in operation, there will be no possibility of a variation in said ratio due to any changes in the total feed rate of the devices 404 and 405 caused by increasing the speed of the motor 425, which may be called the master Selsyn driving motor.

Before describing in detail the control circuit, it may be pointed out that the weighing feeder device 404 is so constructed that it automatically adjusts the feed rate of the associated vibratory feeder 401 to maintain a constant amount of material on the belt conveyor 408 at all times, and the weighing feeder device 405 is of similar construction, it being provided with a similar vibratory feeder 429.

An understanding of the various control circuits can best be had by describing them in connection with the various steps of operation of the system which I shall now proceed to do. Upon the closing of the disconnect switch 403, it is of course evident that power is available on the lines LI, L2 and L8 beyond the switch 403, which lines extend into the bottom of the G. E. control box as shown in Fig. 3 of the drawings. (The letters "G. E. are for identification only and do not signify any particular company.) As clearly shown in Fig. 3 of the drawings, lines LI, L2 and L3 extend into the G. E. control box and then out of it from which they extend to the magnetic contactor or switch 30I which is simply a magnetic switch having a closing coil 430 connected across two of the lines, namely, lines LI and L3 which automatically close the switch whenever lines LI and L3 are energized. Upon the closing of this switch 30I power is supplied to the alternating current motor of the mixed current motor generator 43I (Fig. 3) over lines MGI, MG2 and MG3, the D. C. generator side of which is connected in series with a single phase source of current supplied by lines LI and L2 under the control of various automatic feed rate adjusting mechanism over a circuit which will hereinafter be traced.

In addition to starting rotation of the motor generator set 43I, energy on the lines LI, L2 and L3 is supplied to the safety switch 432 in the G. E. control box (Fig.

Energy from lines L2 and L3 extends to the energizing coil or solenoid 433 of interlock relay 3| 0 (Fig. 2) by way of branch conductors 434 and 435 which closes the contacts of this interlock relay 3I0. As clearly shown in Fig 1 of the drawings, there is a source of relatively low voltage, such as 110 volts, provided by lines 436 and 431 which are controlled by a safety switch 438, which lines 436 and 431 extend to the contacts of the interlock relay 3l0, and when said interlock relay 3I0 is closed this relatively low voltage on lines 436 and 431 is extended to and made available for the control circuit relay 309. The purpose of the interlock relay 3I0 is therefore to insure that the control voltage which is derived from the lines 436 and 431 will only be available in case the power circuit comprising lines LI, L2 and L3 is energized beyond the switch 403, and in case there is any failure of power on said lines LI, L2 and L3, interlock relay 3| 0 will automatically drop out and remove the available low voltage supply from circuit control relay 309.

It is evident that the functions so far described take place immediately upon the closing of the master switch 403 which, in addition to preparing certain relays and circuits, has as its principal function the starting of the motor generator set 43| To start the rest of the system into operation, the operator then pushes the push button start switch 439 (see Fig. 2) which energizes the solenoid 440 of control circuit relay 309 by connecting it across the two energized lines 436 and 431 over the following circuit:

One terminal of solenoid 440 is connected to line 431. The other terminal extends over conductor I to switch 439 which, when closed, completes the circuit to conductor 436. This closing is only momentary and thereafter a holding circuit is provided for solenoid 440 which may be traced from conductor 44I through normally closed stop switch 442, conductors 443 and 444 through the normally closed contacts 445 of timing relay 301, and thence by way of conductor 446 to conductor 436 through the upper contact of the now closed relay 309. The purpose of including the normally closed contacts 445 of timing relay 301 in this holding circuit is to provide a safety shutdown feature which will be described more completely hereinafter.

In the closing of the contacts of control circuit relay 309, it effectively connects conductors 436 and 446 so as to energize the latter from. the former and simultaneously connects conductor 431 to conductor 441 thereby energizing this conductor 441. The presence of power on these two conductors 446 and 441 as thus provided is effective to energize the solenoid or operating coil 448 of the 4-po1e relay 308 through a circuit now to be described.

I I 5. One terminal of solenoid 448 is connected directly to the energized conductor 441 as clearly illustrated. The other terminal of said solenoid 448 extends byway of a conductor 449 to the normally closed limit switch 450 (see Fig. '1) contained inside the master motor driven rheostat 426, which switch 450 is normally closed but which is open when all of the resistance of master motor driven rheostat 426 is put in circuit with the rotor of induction motor 425 and, as will be hereinafter evident, under such conditions the Waytro control box A (see Fig. 2) is eifectively disconnected. With the switch 450 closed, however, as it normally will be, this line extends from conductor 449 to conductor 45I which, as clearly shown in Fig. 2, is connected to conductor 446, thus completing the connection of the solenoid 448 across the energized lines 446 and 441. Solenoid 448, while being energized, of course closes the 4-pole switch of relay 308. Energized lines 441 and 446 are extended by the two center switches of relay 308 to conductors 452 and 453, respectively, to posts H0 and I09, respectively, on the Waytrol" control box A so that these two posts I09 and H0 are thus energized.

It may be further pointed out that another branch of conductor 452 also extends to similar post II 0 on "Waytrol control box B, and post I 09 of said Waytrol control box B is connected to conductor 453 by a branch thereof which extends up to the contacts of a control relay 304 and thence by way of conductor 454 which is connected to post I 09 of "Waytrol control box B As is hereinafter pointed out, relay 304 is under the control of Waytrol control box A, and therefore Waytrol control box B can only be energized after Waytrol control box A is energized.

Before proceeding with a. further description of any of the circuits, it may be well pointed out at this time that Waytrol" control box A controls the weighing feeder device 405 and "Waytrol control box B controls the weighing feeder device 404; that is, Waytrol control boxes A and B are identical and so the description of only one is necessary. The mode of operation of Waytrol control box A will be described hereinafter, but at this time it may be stated that it operates automatically to maintain a predetermined weight of material on the' conveyor belt associated with :13; balanced frame of weighing feeder device From the above description, it is evident that when relay 308 closes its contacts posts I09 and H0 on Waytrol control box A are energized and thus power is available at these posts. Referring particularly to Fig. 6 of the drawings which shows the internal circuits and apparatus of Waytrol" control box A (which also applies to Waytrol control box B), it will be seen that the post I09 is connected to the post I05 and the post H0 is connected to the post I04 and relay 304 by way of conductors 458 and 451 to close the contacts thereof, thus closing the circuit to supply power to the post I09 of Waytrol control box B over conductor 454, post IIO being previously directly connected to energized conductor 441 by way of conductor 452. This of course then energizes the "Waytrol" control box Reverting to Fig. 6 it may be pointed out that the circuits which connect posts I09 and H to posts I and I04, respectively, may be traced as follows: Post I09 is connected to post I05 by way of conductor 458, the rlghthand blade of normally closed knife switch 459 and conductor 480, one branch of which leads directly to post I 05, another branch of which leads by way of fuse 46I and conductor 482 to post III for a purpose hereinafter described.

Post H0 is connected to post I04 by way of conductor 483, lefthand blade of switch ,459, busbar conductor 494, conductor 485, fuse 468, conductor 481 and the center blade of normally closed knife switch 488 which is connected directly to post I04 by a short conductor.

It may further be pointed out that a branch from conductor 485 leads to post I08 by way of fuse 489 and conductor 410 for a purpose hereinafter pointed out.

To summarize briefly some of the later operations which have taken place, it is evident that relays 304, 308, 309 and 3I0 have been energized in response to the closing of start switch 439 and as a result WaytroP' control box A was first energized and thereafter Waytrol" control box B was energized, thus placingthese control boxes on an operative basis. The relay 304 is of course a Waytrol" interlock relay, that is, it interlocks the Waytrol" control box B under the control of Waytrol" control box A.

As previously described, there are conditions under which only one of the Waytrol control boxes will be put into operation and that is the Waytrol" or weighing feeder device 405 which is under the control of Waytrol control box A.

Attention is now directed particularly to Fig. 5 of the drawings and to the circuits and apparatus in the G. E. control box. When the main line switch 403 (Fig. 1) was closed energy was thus delivered to lines LI, L2 and L3 which extend to the G. E. control box and thence to normally closed safety switch 432 therein. The voltage on said lines LI, L2 and L3, such as 440 volts, is automatically applied to the operating coil or solenoid UV of an under voltage relay 8 having four normally opened contacts 412, 413, 414 and 415 associated therewith.

As clearly illustrated in Fig. 5 of the drawings, after the lines LI, L2 and L3 pass through switch 432, each has a number of branches, but since they are all connected together and are electrically the same they will retain the same desi nations LI L2 and L3.

It is manifest that solenoid UV is connected across one branch of lines LI and L2 through short conductors 418 and 411 so that said solenoid UV is always energized as long as there is power on these two lines. The purpose of this under voltage relay 8 is of course to protect the system against under voltage. and the solenoid UV will release on a predetermined low voltage.

Most of the relays in the G. E. control box of Fig. 5 are operated from relatively low voltage, that is, 110 volts in the illustration given which is derived from the Waytrol control box A by virtue of a branch of conductors 458 and 451 which extend from posts I04 and I05 which are energized as previously described and thence to posts I4 and I1, respectively, of the G. E. control box, the circuit being clearly illustrated from Waytrol" control box A, posts I04 and I05 to posts I4 and I1, respectively, by reference to Figs. 2 and 3 of the drawings over the downwardly extending branch of conductors 458 and 451. By virtue of this voltage on posts I4 and I1 the coil LEIA of relay I4 is energized over a circuit which may be traced in Fig. 5 but which is better shown in the simplified circuit of Fig. 10 which includes this relay and the posts I4 and I1. This circuit is from post I4, contacts 418 of relay 8, conductor 418 to one post of solenoid LEIA. The other post of said solenoid LEIA is connected through normally closed safety overload contacts 419 and 480 of relay I 4, thence by way of conductor 48I through normally closed contacts 482 and 483 of safety overload switch 484, then by conductor 485 through contacts 414 of relay 8 to post I1. This energization of solenoid LEIA closes its contacts 488 and 481 thereby extending power lines L3 and L2, respectively. to conductors 488 and 489 to posts RI and R2, respectively, from which said conductors 488 and 489 thence extend to the stator of the driving Selsyn motor 420. At the same time the closing of contacts 488 and 481 also extends power lines L3 and L respectively, to conductors 490 and 49I which extend to posts RBI and RR2, respectively, through heater elements associated with overload switches 482 and 483, respectively, and thence beyond posts RBI and RRZ to one phase winding of the stator of the receiving Selsyn motor 4I5 associated with the weighing feeder device 405.

As previously described, the S-phase windings of the rotors of the Selsyn motors 420 and 8 are connected together over conductors 4H, 8 and H9, and when switch I4 closes its contacts 486 and 481 single phase energy from lines L3 and L2 is delivered to energize one phase of the stators of these two Selsyn motors 420 and H8,

.and this causes the rotors of said motors 420 and M6 to lock into a predetermined position.

It may be pointed out that the safety switches 482 and 483 associated with the lines 490 and 49I are well known overload heater safety switches which open the circuit to coil LEIA of relay I4 in case of an overload in either of the conductors 490 or 49I. Similarly, switches 419 and 480 drop out this relay I4 in case of an overload in conductors 488 or 489.

To summarize briefly, the operation of relay I4 has thus placed single phase voltage on the stators of the two Selsyn motors H8 and 420 and locked the rotors thereof into a predetermined position. As previously described posts I09 and H0 of the Waytrol control box B (Fig. 2) were energized over conductors 452 and 454, and these posts I09 and H0 are connected to the posts I04 and I05 of the Waytrol" control box B in the same manner that the similarly designated posts are so connected in the Waytrol control box A.

From posts I 04 and I05 of Waytrol control box B the low voltage volts in the illustration given) is extended over conductors 492 and 493 to posts 2I and 24, respectively, on the G. E. control box.

Referring particularly to Figs. 5 and 11 of the drawings, it will be seen that placing power on posts 2| and 24 energizes the solenoid LE2A of relay i9. Post 2| is connected to one terminal of solenoid LE2A through conductor 494 which includes the contact 413 of relay 8 in circuit therewith, and post 24 is connected through conductor 495 thence through contact 412, of relay 8, overload contacts 496 and 491 of switch l9 thence by conductor 498 through normally closed contacts 499 and 500 of overload switch 484 then by an upper branch of conductor 498 to the other terminal of solenoid LE2A. The energization of the solenoid LE2A of relay l9 closes its contacts at SM and 502 to connect posts R4 and R5 to power lines L3 and L2, respectively, by way of conductors 503 and 504 which carry heating units associated with the safety contacts 496 and 491 of relay l9. Conductors 503 and 504 extend beyond posts R4 and R5, respectively, and to one winding of the 3-phase wound stator of the driving Selsyn motcr 4| 5 thus energizing a single phase of the stator thereof.

At the same time the closing of contacts 5M and 502 extends lines L3 and L2 to posts RR4 and RR5, respectively, by way of conductors 505 and 506 through heaters associated with safety overload switch contacts 499 and 500 of switch 484. Conductors 505 and 506 extend beyond the posts RR4 and RR5 to one phase winding of the stator of the receiving Selsyn motor 4 associated with the weighing feeder device 404. It is thus evident that the energization of the solenoid LE2A of relay l9 energizes one phase of the stator of the Selsyn transmitting motor M5 and one phase of the stator of the Selsyn receiving motors 4H, and since their B-phase rotors are connected together by conductors 4| 2, M3 and M4 as previously described said rotors will be locked in step by this application of single phase current to the stators.

It is of course understood that to obtain synchronous operation of the Selsyn transmitters M5 and 420 and their associated receivers 4H and 6, respectively, it is necessary to energize the stators of both with B-phase current instead of single phase current which alone has so far been appliedby the described mechanism. It is desirable that the single phase connection between the stators be firstmade as previously described and thereafter connections be made to effect the 3-phase energization of said stators. To accomplish this feature I provide timing relays 2| and -40 which will now be described and which, it may be stated, are operated to control contactors 22 and I1, respectively.

As previously described, the low voltage, that is, H volts, was applied to the terminals of coil LEIA in response to certain previous conditions which were described in detail. This voltage is also applied to start the operation of the motor of the timing relay 40 over a circuit which extends from conductor 418 by way of conductor 501 to the motor of the timing relay 40 and thence through conductor 508 to a position on the other terminal of solenoid LEIA. This energization of the motor of relay 40 is through normally closed contacts 509 thereof, and after a predetermined time interval relay 40 closes contacts I0 by means of a cam which is operated by the motor M thereof which connects operating coil or solenoid LEIB of connector l1 directlyacross the energized lines 501 and 508, that is, conductor 508 extends directly from one terminal of solenoid LEIA to one terminal of solenoid LEIB.

Branch 501 which extends from conductor .418 is extended through switch 5I0 and thence to a continuing branch 5 which forms a continuation of conductor 501 when switch M0 is closed. Conductor 5 extends to post 20 forming one terminal of solenoid LEIB; The energization or solenoid LEIB closes the contacts N2 of contactor l1 and thereby extends line Ll to conductor 5l9 which leads to post R3 and extends beyond said post R3 by way of two branches leading to the third wire of the stator 01' driving Selsyn motor 420 and receiving Selsyn motor 6. This of course provides the application of 3-phase power from lines Ll, L2 and L3 to the stators of the Selsyn motors 8 and 420, and thereafter any rotation of their rotors will be in synchronism, and consequently Selsyn motor 420 will drive Selsyn motor 6.

The closing of switch 5! of timing relay 40 with the consequent connection of line 5 to a source of power as previously described also energizes coil or solenoid LEM of transfer relay or contactor 44 by virtue of the fact that one post of the coil LEM is directly connected to conductor 5| I, the other post being connected through normally closed overload contactors 5M and 5|5 to a branch of conductor 485. In other words, switches l1 and 44 operate simultaneously after timing relay 40 has closed its contacts 5I0.

Solenoid LEM upon being energized closes the contacts 5l6, 5H and 5l8 of relay 44 which thus extend the lines Ll, L2 and L3, respectively, to conductors H9, 520 and 52L the first and the last through heating elements associated with overload contacts 5 and 5l5, which conductors 5|9, 520 and 52! extend to-posts Tl, T2 and T3, respectively, and beyond said posts to the stators of the induction motor 425 which is the main drive motor for the Selsyn transmitter. This of course supplies 3-phase power to said induction motor 425 and starts it to rotate at an ultimate speed which will be determined by the master motor driven rheostat 426.

It is of course manifest that since the Selsyn transmitters M5 and 420 have previously been connected with their receivers 4H and 4| 6, respectively, that the conveyor belts of the weighing feeder devices 404 and 405 will thus start to rotate at a speed determined by the speed of rotation of motor 425 and by the variable speed Selsyn drive 421, assuming of course that the magnetic clutch 428 is connected to couple the Selsyn transmitter motor 5 for driving.

When the solenoid LE2A of contactor l9 was energized, the timing relay 2| was simultaneously placed into operation, the circuit therefore being traced from the terminals of said solenoid LE2A by way of conductors 498 and 522. After a predetermined time interval for which this timing relay 2| is set, the cam thereof closes the contacts 523 thus connecting one post of solenoid LE2B of connector 22 to one energized post of solenoid LEZA over conductors 522 and 524, the other terminal of said solenoid LE2B being connected to conductor 498.

It is of course to be understood that this action took place simultaneously with the previready performed its operation. When solenoid LE2B is thus energized, it closes its contacts 525, 526 and 521, the first of which extends line Ll to conductor 528 which leads to post R6 and beyond post R6 it has two branches, one of which extends to the third connection of the 3-phase stator of driving Selsyn motor 5 thus providing 3-phase power on the stator thereof. and the other branch of which extends to the third connection of the 3-phase stator winding of receiving Selsyn motor 4!! associated with weighing feeder device 404. In short, the contactor 22 has changed over the single phase application of power to the Selsyn motors 4!! and 5 to 3-phase power, thus insuring their rotation in unison as previously described.

The contacts 526 and 521 operate to energize the magnetic clutch 428 associated with driving Selsyn motor 5 in a manner now to be described. 7

Two conductors 529 and 530 lead from magnetic clutch 428 (Fig. 3) to posts 26 and 21 on the G. E. control box which form the output circuit of a rectifier 53!, the input circuit of 539 and power driven rheostat 540 and thence normally through the hand operated rheostat 54! because of the normally open condition of relay 542, and then from conductor 543 directly to conductor 545 because of the normally closed contacts of relay 546, and then along conductor 545 to the energizing coil of feeder 429 associated with weighing feeder device 405 (see Fig. 1) from whicha conductor 541 extends to and through the upper contacts of relay 302 which are now closed, thence to conductor 548 which leads directly to one brush of the D. C. motor of the motor generator set 43! (see Fig. 3). The other brush of said D. C. motor is connected directly which is provided by continuations of conductors 529 and 530 which extend to terminals of contacts 526 and 521. The other terminals of contacts 526 and 521 extend by conductors 532 and 533 to posts 8 and respectively, and beyond said posts, the former connects to previously described conductor 45! whichis supplied with power over a previously described circuit. Conductor 533 extends upwardly along side conductor 45! (see Fig. 3) until it connects with previously described conductor 441 which is connected to the other side of the source of power of low voltage. As a consequence, the magnetic clutch 428 is energized upon the actuation of contactor relay 22 thus insuring a drive connection for the sending Selsyn motor 4 !5 when relay contactor 22 is energized.

Furthermore, at the time solenoid LEIB was energized it is of course evident that the post 'thereof was energized and there is a conductor 534 (see Fig. 2) which extends from post 20 to one terminal of the energizing coil or solenoid 535 of relay 302, the other terminal of which solenoid 535 is connected by conductor 535 to post of Waytrol" control box A which is connected to the other side of the source of low voltage as previously described. Consequently solenoid 535 is thus energized by timing relay 40, the result of which is to extend main lines L2 and L3 to conductors 531 and 538, the former of which leads through the lower pair of contacts of relay 302 and then extends through'the ammeter 533 from which conductor 531 extends through the motor driven rheostat 540, and

thence returns to a branch point, one branch of said conductor 531 leading to a manually adjustable rheostat 54! and another branch extending to post H3 of Waytrol" control box A. From post !!3 the one branch of conductor 531 extends to the normally opened contacts of magnetic switch or relay 542 (see Fig. 6), the function of which will be explained hereinafter. The other branch of conductor 531 after passing through rheostat 54! connects to a conductor 543 having two branches, one of which leads to post H4 of Waytrol control box A, the other one of which extends to hand operated rheostat 544 and through said rheostat 544 to a conductor 545, one branch of which extends to post !!5 on Waytrol" control box A.

By referring to Fig. 6 of the drawings, it will be seen that the conductors 543 and 545 are normally connected together by the normally closed contacts of a magnetic switch-of relay 546, the function of which will be described hereinafter so that conductors 543 and 545 are normally connected together, and thus hand operated rheostat 544 is normally shunted. Thus from conductor 531 the normal circuit will extend from by the feeder 429 from the hopper associated line L2 and switch 30! first through ammeter *1'5 by conductor 538 to the line L3 in switch 30!. As a consequence of the closing of the contacts of this relay 302, mixed current, that is, alternating current from lines L2 and L3 in s ries with direct current from the generator of motor generator set 43!, is thus fed to the energizing coil of the feeder 429 which is a mixed current type of feeder. In this circuit there is also normally included the power driven rheostat 540 and the hand operated rheostat 54!. It is of course evident that the rate of feed of material therewith will be governed by the amount of resistance in series therewith which will be the sum of the resistance of rheostats 540 and 54! under normal conditions. It may be stated at this time that control mechanism which I shall describe hereinafter is provided which is under the control of the balanced belt conveyer of the weighing feeder device 405 which will operate automatically to adjust the value of the effective resistance of rheostat 540, and under certain conditions will shunt the resistance of hand resistor 54! and under other conditions will place both rheostats 54! and 540 in series with the winding of feeder 429. In short, the feed rate of feeder 423 is automatically adjusted to maintain the weight of material on the weighing belt of weighing feeder device 405 substantially constant at all times.

In a similar manner when timing relay 2 (see Fig.5) closed its contacts 523, it energized post 25 and as clearly seen by reference to Fig. 2 of the drawings, a conductor 543 extends from post 25 to one terminal of solenoi \of the operating coil 5500f relay 303, the other terminal of which is connected by a conductor 55! to the post I!! of Waytrol control box B which is connected to the other line of the source of low voltage as previously described. As a consequence, when contacts 523 of timing relay 2! were closed, it also caused the energization of solenoid 550 of relay 303 thereby closing its contacts. Relay 303 in closing its contacts is. effective to connect mixed current to the feeder 401 of weighing feeder device 404 in series with the motor driven rheostat 552, and the hand operated rheostat 553 as well as ammeter 554, a hand operated rheostat 555 being normally shunted by virtue of the normally closed contacts of the relay associated with posts !!4 and I! 5 of Waytrol" control box B which is of course a duplicate of Waytrol control box A as above described. This circuit may be traced from lines L2 and L3 of switch 30! as follows:

From line L2 the circuit leads by way of conductor 531 to the lower lefthand terminal of relay 303, and thence from the lower righthand terminal thereof by way of conductor 556 to the winding of feeder 401 of the weighing feeder device 404, thence by way of conductor 551 to aaaaise the post H of "Waytrol" control box 3 which, as previously mentioned, is normally directly connected to post I, thence from post 4 by way of conductor 558 through hand rheostat 553, thence by way of conductor 559 through motor driven rheostat 552,, thence by conductor 560 through ammeter 554 from which conductor 560 then extends through the upper contacts of relay 888 and connects to conductor 548 which, as previously described, is connected to one of the brushes of the direct current generator of the motor generator set 43L the other brush of which is directly connected by conductor 538 to the line L3 at switch 60!.

It is thus evident that timing relay 2| has energized the feeder 401 associated with the weighing feeder device 404 with mixed current including power driven resistors 552 and 553 normally in series therewith, both of which are under the control of the "Waytrol" control box B.

The system may be operated either manually or automatically to adjust the speeds of the two conveyor belts associated with the weighing feeder devices 484 and 465 because, as previously described, this is the manner in which the total output of these two devices 484 and 405 is controlled, and this is done without any alteration whatever in their feed ratio. I shall now describe the manual operation of the system.

Referring to Fig. 5 of the drawings, it will be seen that I have provided a fast push-button switch 56| and a slow" push-button switch 562.

extend from the rotor of induction motor 425 to resistors 518, 580 and 56L respectively, of the master motor driven rheostat 426 and thus are eflectively connected in series therewith by the position of the adjustable 3-pole arm 582 of said master motor driven rheostat 426.

As previously mentioned, the speed of the motor 425 adjusts the total output of the two weighing feeder devices 404 and 405 without disturbing their feed ratio in any manner. In case the push-button 56| is released, relay 42 is immediately released and master motor driven rheostat 426 stays in any position to which it has been adjusted. In case it is desired to decrease the speed of the motor 425 and consequently decrease the total feed of the two weighing feeder devices 404 and 405, the slow switch 562 (Fig. 5) is'closed thus extending energized line 532 over conductor 566 through switch 562 Upon closing the fast push-button 56!, voltage previously described, is connected to the other line of the source of low voltage. This energizes solenoid LEF and closes its normally opened contacts 566 and 561 and opens its normally closed contact 568.. The closing of contacts 566 and 561 closes a circuit from the secondary of a transformer 569 by way of conductors 510 and 5', the primary of which transformer is connected to lines L2 and L3, which conductors 510 and EH are thus connected to conductors 512 and 515, respectively, leading to and beyond posts 28 and 30, respectively, and extending to the master motor driven rheostat 426 (see Figs. 3 and 7).

As clearly shown in Fig. 7, conductor 518 extends to one brush of the armature of a reversible motor 514 which drives the motor driven rheostat 426 and is provided with a pair of separate field coils which, when selectively energized, cause the motor to rotate in reverse directions in a well-known manner.

As also'clearly shown in Fig. 7, conductor 512 extends through a limit switch 515 which is normally closed but opens when all of the resisance' of rheostat 426 is cut out through said switch 515 thence through one of the field windings of the motor 514 and to the other brush of he armature thereof. It, is thus evident that so long as the fast switch 56| (Fig. 5) is held closed, relay or contactor 42 has its contacts closed, energizing motor 514 (Fig. 7) of the master motor driven rheostat 426 to adjust said rheostat to reduce the eflective resistance which is connected in series with the wound rotor of the induction motor 425. In this connection it is obvious that three conductors 516, 511 and 518 to conductor 583 through normally closed switch 568 of relay or connector 42 and thence to one terminal of the operating coil or solenoid LES of relay or connector 4|. The other terminal of solenoid LES is connected to the other low voltage line by conductor 538 as previously described. Solenoid LES when energized closes its normally open contactors 584 and 585 and opens its normally closed contactor 565. contactor 584 when closed extends previously described conductor 510 to conductor 586 which extends to and beyond post 29 and thence to master motor driven rheostat 426 (Figs. 3 and 7) which conductor 586 extends through normally closed limit switch 581 and thence to the other winding oi" the operating motor 514 which is connected to one brush of the armature thereof. Limit switch 561 is only opened when all of the resistance of rheostat 426 is in circuit and of course under these conditions it is impossible to insert more resistance or to reduce the speed of reduction motor 425 and the only way the rheostat 426 can thus be adjusted isto decrease the effective resistance thereof to increase the speed of motor 425.

Conversely, when all the resistance of rheostat 426 is effectively cut out and switch 515 is open, the only way the rheostat can be adjusted is to insert more resistance. to decrease the speed of induction motor 425. The closing of contact 585 of relay 4| (Fig. 5) connects conductor 51| with previously described conductor 513 which, as previously described, leads to the other brush of the armature of motor 514. In other words, conductor 513 is common to the two relays or connectors 4| and 42 and when either is operated this conductor is connected to conductor 51|. Conductors 512 and 586, however, are individual to the relays or connectors 42 and 4|, respectively, and thus provide for the selective adjustment of the master motor driven rheostat 426 in reverse directions. 1 It is to be noted that operating coil LES of connector 4| includes normally closed switch 568 of relay or connector 42 and conversely operating coil LEF of relay or connector 42 includes normally closed switch 565 of relay or con'' nector 4|. Consequently, when either relay or Y connector 4| or 42 is energized, it is impossible to energize the other because of the opening of the associated normally closed switch 565 or 566, as the case may be. It may be pointed out thata simplified circuit for controlling the solenoids LES and LEF is shown in Fig. 9 of the drawings.

To provide for theautomatic control of the master motor driven rheostat 426 and thus to adjust automatically the feed rate of the material received by the elevator 400, I provide a current transformer 566*(Fig. 1) in association with one of the lines, such as the line L3, after it has passed through switch 402 to the motor 40I of the elevator 400. As previously indicated, instead of the elevator 400, there may be a conveyor or crusher.

From current transformer 588, conductors 589 and 590 extend to posts I and 6, respectively, on the G. E. control box (Figs. 3 and 5) and from said posts to the terminals of a solenoid 59I having associated therewith a normally balanced armature 592, which solenoid and armature form a part of relay I2. Shunted across the terminals of solenoid 59I is a variable rheostat 593 which may be adjusted by hand to adjust the effective value of the shunt so as to adjust the balanced condition of armature 592 to correspond to any predetermined current flow in the line L3 through transformer 566. To, make the automatic control of the master motor driven rheostat 426 effective, the automatic control switch 594 (Figs. 5 and 9) is closed and this eileciively connects the energized conductor 532 through a periodically closing contact 595 of timer I3, then by conductor 596 through switch 594 to conductor 59! which is connected to the armature 592 of the normally balanced relay I2. It may be pointed out that the timer I3 has a motor 508 which is directly connected across the energized lines 532 and 539 to run continuously whenever these lines are energized and which periodically opens and closes the contacts 595 so that armature 592 is connected to conductor 532 when automatic switch 594 is closed only for predetermined recurring intervals. This of course produces a step by-step adjustment of the master motor driven rheostat 426 whenever relay I2 becomes unbalanced thus effecting a time delay which prevents hunting and allows the load on the elevator 400 to reach a condition of equilibrium.

As clearly seen by reference to Fig. 5 of the drawings, the relay I2 is provided with an upper contact 599 which is connected to a branch of.

the previously described conductor 564. It is also provided with a lower contact 600 which is connected to a branch of the previously described conductor 563. Thus, in case the current in the transformer 566 is reduced to a predetermined value, armature 592 will move upwardly to make connection with upper contact 599 which will energize solenoid LEI" with the results previously described in connection with the energization of said solenoid, namely, to increase the speed of induction motor 425 by adjusting master motor driven rheostat 426. This of course will continue so long as the contacts 595 of timer I3 .are closed unless the current flowing through transformer 566 is increased to reestablish the armature 592 of balanced relay I2. An overload on the line L9 will of course increase the current in transformer 586 to pull the armature 592 against a biasing spring to make connection with contact 600 which energizes solenoid LES to reduce the speed of induction motor 425 in a manner which is obvious from previous description.

Attention is now directed to the structure in the Waytrol control box A and the associated mechanism which is operative to maintain at all times a constant amount of material on the belt conveyor associated with the constant weight feeder device 405. Referring first to Figs. 1, 2 and 3 of the drawings, it will be seen that posts III, I02 and I03 of Waytrol" control box A are connected by conductors SM, 602 and 603, re-

spectiveiy, to a control tube box 604 which is shown in detail in Fig. 4 of the drawings. Within said box 604 is a pivoted frame 605 which carries a pair of mercury tube switches 606 and 601. Conductor 602 is common to these two switches and conductor I is individual to switch 606, while conductor 603 is individual to switch 601. The frame 605 is controlled by the frame of the continuous weighing belt conveyor, and when said weighing conveyor is in a balanced condition, both the switches 606 and 60! are in open circuit condition. In case the material on the belt conveyor is too light, frame 605 tilts to close the contacts on switch 606 thus connecting conductors 60I and 602 which connects posts lol and I02 of "Waytrol" control box A. This causes a solenoid 608 of a relay 609 to be energized (see Fig. 6) over the following circuit.

From bus-bar conductor 464 which was energized as previously describedthrough conductor 6I0, normally closed contacts 6II of relay M2, and thence directly to one terminal of solenoid 606, the other terminal of solenoid 606 is connected over conductor 6I3 to post IOI which, as just previously stated, is connected to post I02 by switch 606, conductors 60I and 602, and thence from post I02 through the lefthand contact of switch 468 to a bus-bar conductor 6I4 which is connected to the conductor 462 and post III which is energized from the other line of the low voltage source as previously described; that is, bus-bars 464 and (H4 are connected to the two lines of the low voltage source of supply over circuits previously described.

It may be pointed out that when energy was supplied to the Waytrol" control box A from the low voltage source, a white signal light 6I5 was energized because one terminal of it is connected to bus-bar conductor 464, and the other terminal of it is connected to conductor 460 which is connected directly to the other bus-bar conductor 6 through fuse 46l. When solenoid 608 is thus energized, it pulls its armature 6I6 into contact with a lower terminal which connects bus-bar 464 with one terminal of the operating coil or solenoid 6II of a multiple pole relay, the other terminal of which solenoid 6II is connected directly to bus-bar H4. The solenoid 6II when thus energized closes a plurality of circuits. The lefthand contact connects a green signal light 6I9 directly across the bus-bars 6 and 464 over obvious circuits.

The second contact from the left connects the bus-bar 6I4 to a conductor 620 which extends to post I 06 and beyond post I06 to form two branches (see Figs. 2 and 3), the lower one of which extends to the terminal of one field coil of reversible motor 62I, the center tap of which field coil is connected to one brush of the annature, the other brush of which is connected by a conductor 622 to and through the post I06 which, as previously described, is connected by conductor 410, fuse 469 and conductor 465 to bus-bar 464. This of course starts rotation of the motor 62I to drive the motor driven rheostat 540 in a direction to reduce the effective resistance thereof which of course increases the feed rate of the vibratory feeder 429 associated with the weighing feeder device 405. At the same time the third set of contacts of relay 6I6 closes the circuit from bus-bar conductor 6 by way of conductor 623 to one terminal of solenoid 624 of normally open relay 542, the other terminal of which is connected directly to bus-bar 464 over an obvious conductor.

The energization of solenoid 624 closes the contacts thereof which connect conductors 531 and 543 which are connected to posts H3 and H4, respectively, thus shunting out the resistance of rheostat 54I. This shunting of rheostat SM is of course automatic and immediately iiicreases the feed rate of vibratory feeder 429 of weighing feeder device 405 to increase the feed rate of the material from the hopper associated therewith to the weighing conveyor. It is obvious that rheostat 54I will be shunted and rheostat 540 will move to decrease its eifective resistance simultaneously, and both actions will continue' until the normal load is again present on the belt conveyor of the weighing device 405 whereupon mercury switch 606 (Fig. 4) will open its contacts and the relays which have been operated in the "Waytrol control box A will immediately drop out.

The rheostat SM is adjustable so that the amount of the immediate increase in feed rate in feeder 429 may be adjustably determined. Should an overload condition develop on the weighing conveyor of the device 405 frame 605 will tilt in an opposite direction from that above described and close the contacts of mercury switch 601 which by way of conductors 602 and 603 interconnects posts I02 and I03, thus connecting bus-bar 6I4 to one terminal of the solenoid 625 of relay H2.

The circuit from bus-bar 6I4 extends through the lefthand terminal of knife switch 460 to post I02, thence to post I03 which is connected thereto over wires 602 and 603 and switch 601 as just described. From post I03 conductor 626 leads to one terminal of the solenoid 625. The other terminal of solenoid 625 extends to bus-bar 464 by way of conductor 621, normally closed armature MB of relay 609 and thence to bus-bar 464 by an obvious conductor. It is to be noted that solenoid 625 can only be energized when solenoid 603 is de-energized, and vice versa. This of course provides an interlock between the two relays 600 and M2 so that onlyone can be energized at a time. When solenoid 625 is energized, its armature 6 opens the normallyclosed circuit and connects conductor 6I0 leading from bus-bar 464 to one terminal of a solenoid 628 of a relay 629. The other terminal of solenoid 628 is connected directly to bus-bar 6I4 over an obvious conductor.

Solenoid 628 when energized closes three difierent circuits now to be described. The first circuit is to signal lamp 630, one terminal of which is connected to bus-bar 464, the other of which is connected to conductor 63I to the lefthand contacts of relay 629 to bus-bar 6I4. The second pair of contacts from the left of relay 629 extend the circuit from bus-bar 6I4 to conductor 632 which leads to post I01 and beyond post I01 to one end of the field coil of motor 62I (seefFig. 3) associated with the motor driven rheostat 540 which of course causes this motor 52I to operate in a reverse direction than that previously described in response to an overweight on the weighing belt of weighing device 405. The return circuit for this motor MI is of course by way of conductor 622 as previously described.

The third pair of contacts on relay 629 when closed extend bus-bar 6I4 to one terminal of the solenoid 633 of the normally closed relay 546 over an obvious circuit, the other terminal of said solenoid 633 being connected to bus-bar 464 by way of conductor 465. When solenoid 633 isthus energized, it opens its contacts and thus removes the shunt connection normally existing between conductors 543 and 545 which of course removes the previously described normal short circuit of hand operated rheostat 544. This of course inserts the efiective resistance ofrheostat 544 in series with the vibratory feeder 423 associated with weighing device 405 and instantly reduces its feed rate. The motor driven rheostat 540 also starts to act to increase the resistance in series with said motor 429 and the reduced feeding rate of said feeder 429 is thus maintained until the weighing conveyor of weighing feeder device 405 is again restored to its normal condition of equilibrium, whereupon switch 601 opens and restores the relays in the Waytrol control box A to their normal condition.

, The Waytrol" control box B and the associated apparatus including the hand operated rheostats 553 and 555 and the motor driven rheostat 552 operate in a manner which is the same as that just described for equivalent apparatus controlled by Waytrol control box A; that is, rheostat 54I corresponds to rheostat 553, rheostat 544 corresponds to rheostat 555, and motor driven rheostat 540 corresponds to motor driven rheostat 552. The Waytrol control box B of course controls the feeder 401 associated with the weighing feeder device 404, and there is a control switch associated with the belt conveyor thereof similar to the switch shown in Fig. 4 of the drawings. Except for a particular situation which is hereinafter described, the circuits leading to and from Waytrol control box B are believed so obvious as not to justify. individual description. 1

There are certain alarm and protective devices associated with the system which shall now be described. In the case where the weighing conveyor associated with the weighing feeder device 405 was light and thus required more material on it to produce a stabilized condition, the relay 6I6 (Fig. 6) of the Waytrol control box was energized and connected with the bus-bar 6I4 through the second contact from the left to the post I06 from which extends conductor 620. This conductor 620 has two branches, one of which leads to the motor 62I of motor driven rheostat 540, the other one of which extends upwardly (see Fig. 2 of the drawings) and through the lower pair of contacts of relay 308 and then by way of a conductor 634 to one post of a motor driven timing relay 305, the other post of which is directly connected to the conductor 441 so that the low voltage previously mentioned is applied directly to the terminals of the timing relay 305.

After a predetermined time, the normally open contacts 635 of timing relay 305 will be closed in case this voltage is maintained on said relay 305 in which case conductor 441 is extended by way of conductor 636 to an alarm 631, one terminal of which is connected directly to conductor 446 by way of conductor 630. In other words, if the Waytrol control box A has its relay 6I8 energized for a predetermined length of time, alarm 631 will be sounded. More generally, this means if the weighing conveyor of the weighing feeder device 405 does not receive sufiicient material to be brought into equilibrium for an extended period which might occur, for example, as the hopper associated with the feeder 429 became empty, the alarm 631 will sound calling the attendants attention the fact that something is wrong In a similar manner, underweight on the weighing conveyor of the weighing feeder device 404x-.w ilL apply potential of post I06 of "WaytroP control box B, which potential is extended by conductor 839 through the upper pair of contacts of relay 300 and thence by conductor 040 to one post of the timing relay 303, the other post of which is connected directly to the other energized conductor 441. Timing relay 303 is thus thrown in operation whenever the weighing belt associated with weighing device 404 is light, and if this condition maintains for a predetermined time as determined by the timing of relay 808. its normally open contacts 54! are closed, and since these contacts are in vator 400 being illustrated in the drawings, thus producing a mixture of materials having a desired ratio. This ratio is indicated at all times at the operator's station, which may be either adjacent to or remote from the weighing devices 404 and 405, by the tachometers 423 and 424. The total amount of material delivered to the elevator 400 may be adjusted without in any way affecting the ratio and entirely independent of any characteristics of any feeders or weighing conveyors by adjusting the speed of the master parallel with contacts 035 of relay 305 this will also cause the sounding of alarm 531.

As previously described at the outset of this description, the holding circuit for the control circuit 308 which controls the starting and stopping of substantially the entire system, included the normally closed contacts 445 of timing relay 301. The function of this timing relay 301 is to shut down the entire system in case the alarm 331 is allowed to operate for a prolonged predetermined length of time. This is effected by virtue of the fact that the clutch coil of the timing motor of relay 301 is connected directly across the conductors 538 and 538 which supply energy to the alarm 531. The armature of this relay is directly connected across the energized .conductors 440 and 441. Consequently, whenever alarm 431 is energized timing relay 301 starts tocount time and unless the faulty condition is rectified to shut ofl the alarm 631 in a predetermined length of time, timing relay 301 automatically opens its contacts 445 at the end of the time period and this breaks the holding circuit for solenoid 440 of relay 308 which automatically shuts down the entire system insofar as it is controlled by relay 308 as previously described which includes substantially everything except the rotation of the motor generator set 43!.

As-previously stated, it is possible to operate the weighing feeder device 405 alone, but it is not possible to operate the weighing feeder device 404 alone, and in case it is desired to operate the weighing feeder device 405 alone it is only necessary to open the switch 450 and the Waytrol" control box 3 to disable the weighing feeder 404 and its control devices. In the operation of the device under conditions in which both of the weighing feeder devices 404 and 405 are operated, it is of course evident that each will maintain a predetermined amount of material on its weighing conveyor at all times. These amounts are preferably exactly. the same and in any event they are not changed while the system is in operation, because it has been found in practice that if an attempt is made to adjust the weights of material on two weighing devices while running the conveyors at the same speed, extreme accuracy is not realized, but I have discovered that if the weights of material on the two or more weighing feeder devices are maintained constant, a definite ratio which may be widely adjusted can be maintained between the outputs thereof by adjusting the speeds of the weighing conveyors.

The material from the two weighing devices 404 and 405 is delivered by chutes 421 and 422 to the elevator, conveyor or crusher, and eledrive motor 425. The feed ratio of the two weighing feeder devices 404 and 405 may be readily adjusted by the variable speed Selsyn drive 421. The total out-put of the weighing feeder devices 404 and 405 may be adjusted either manually or automatically. When adjusted automatically the load on the elevator 400 or conveyor or crusher'which replaces it will be automatically maintained substantially constant within limits as determined by the operator. The system is provided with numerous interlocks as previously described and an alarm which indicates an abnormal condition. such as lack of proper material on the weighing conveyors of one of the weighing feeder devices 404 and 405, and unless the undesirable condition is corrected within a predetermined time the entire system is shut down automatically requiring it to be started again manually by an operator.

The total travel recorded by odometers 423, 424 gives the total feet of belt travel for each belt of devices 404 and 405. This multiplied by the counter-poise setting of the associated weighing device gives the total poundage feed by each machine. This is an important feature of my invention.

It is of course evident that many features of the invention, while realizing their greatest efflciency in the complete system which I have disclosed, may be independently employed. For example, the automatic means for maintaining a constant load on the elevator 400 might well be provided entirely independently of the extremely elaborate and weighing devices 404 and 405 and might be controlled in connection with one or more feeders, such as the feeders 401 and 429, feeding directly into the elevator 400 or the crusher or conveyor substituted therefore.

Other legitimate sub-combinations will be suggested to those skilled in the art which may have utility separate from the complete system.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and I therefore wish not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

1. In a feeding system the combination with a power driven material receiver, of an electric motor for driving said receiver, feeder mechanism for feeding material to said receiver, and means responsive to the current flow to said motor to adjust the feed rate of said feeder mechanism to maintain a fairly constant current flow to said motor.

2. In a feeding system the combination with a power driven material receiver, of an electric motor to adjust the feed rate of said feeder mechanism to maintain a fairly constant current flow to said motor.

3. A variable rate accurate weighing apparatus comprising a balanced conveyor, means for keeping a constant weight of material thereon, a variable speed motor for driving said balanced conveyor, remote means for adjusting the speed of said motor, and means for accurately measuring and indicating the speed of said motor at said remote means, said remote means including a rotating electrical machine which rotates continuously with the motor of said balanced conveyor.

4. Mixing feeder apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources comprising a constant weight feeding device associated with each source, each of said constant weight feeding devices comprising a variable speed conveyor mounted on weighing apparatus, a feeder, and mechanism controlled by the balanced or unbalanced condition of said weighing apparatus to control said feeder thereby to maintain a substantially constant weight of material on said I conveyor independently of the speed thereof, and

means for varying the speed ratio of the conveyors of said constant weight feeding devices including an independent rotary driving device for each conveyor and mechanism for driving said rotary driving devices from a common rotary motor at least one such drive including a variable ratio drive means.

5. Mixing feeder apparatus comprising a material receiver, means for feeding material theretofrom a plurality of sources comprising a constant weight feeding device associated with each source, each of said constant weight feeding devices comprising a variable speed conveyor mounted on weighing apparatus, a feeder, and mechanism controlled by the balanced or unbalanced condition of said weighing apparatus to control said feeder thereby to maintain a substantially constant weight of material on said conveyor independently of the speed thereof, and means for varying the speed ratio of the conveyors of said constant weight feeding devices including independent electrical driving connections comprising a rotary receiver motor on the conveyor and an interconnected remote rotary driver motor, and mechanism for driving said driver motors from a common variable speed rotary motor through variable gearing whereby the speed ratio of said driver motors may be varied.

6. Mixing feeder apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources comprising a constant weight feeding device associated with each source, each of said constant weight feeding devices comprising a variable speed conveyor mounted on weighing apparatus, a feeder, and mechanism controlled by the balanced or unbalanced condition of said weighing apparatus to control said feeder thereby to maintain a substantially constant weight of material on said conveyor independently of the speed thereof, and means for varying the speed ratio of the conveyors of said constant weight feeding devices including independent electrical driving connections for each, each such driving connection comprising a rotary receiver motor on the conveyor and an interconnected remote rotary driver motor, and mechanism for driving said driver motors from a common rotary motor. through variable gearing whereby the speed ratio of said driver motors may be varied.

7. Mixing feeder apparatus comprising a niaterial receiver, means for feeding material thereto from a plurality of sources comprising a constant weight feeding device associated with each source, each of said constant weight feeding devices comprising a variable speed conveyor mounted on weighing apparatus, a feeder, and mechanism controlled by the balanced or unbalanced condition of said weighing apparatus to control said feeder thereby to maintain a substantially constant weight of material on said conveyor independently of the speed thereof, and means for varying the speed ratio of the conveyors of said constant weight feeding devices including independent electrical driving connections for each, each such driving connection comprising a rotary receiver motor on the conveyor and an interconnected remote rotary driver motor, mechanism for driving said driver motors from a common variable speed rotary motor through variable gearing whereby the speed ratio of said driver motors may be varied, and means adjacent said last named mechanism for measuringthe speeds of said driver motors.

8. Mixing feeder apparatus comprisnig. a material receiver, means for feeding material thereto from a plurality of sources comprising a constant weight feeding device associated with each source, each of said constant weight feeding devices comprising a variable speed conveyor mounted on weighing apparatus, a feeder, and mechanism controlled by the balanced or unbalanced condition of said weighing apparatus to control said feeder thereby to maintain a substantially constant weight of material on said v conveyor independently of -the speed thereof, and

means for varying the speed ratio of the conveyors of said constant weight feeding devices including independent electrical driving connections for each, each such driving connection comprising a rotary receiver motor on the conveyor and an interconnected remote rotary driver motor, mechanism for driving said driver motors from a common rotary motor through variable gearing whereby the speed ratio of said driver motors may be varied, and means adjacent said last named mechanism for measuring the speeds of said driver motors.

9. Mixing apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources including a variable speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including an independent rotary driving device for each conveyor and mechanism for driving said rotary driving devices from a common rotary motor, at least one such drive including a variable ratio drive means.

10. Mixing apparatus comprising a material receiver, means for feeding material thereto'from a plurality of sources including a variable speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including independent electrical driving connections for each, each such driving connection comprising a rotary receiver motor on the conveyor and an interconnected remote rotary driver motor, and mechanism for driving said driver motors from a common variable speed rotary motor through variable gearing whereby the speed ratio of said driver motors may be varied.

l1. Mixing apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources including a variable speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including independent electrical driving connections for each, each such driving connection comprising a rotary receiver motor on the conveyor and an interconnected remote rotary driver motor, and mechanism for driving said driver motors from a common rotary motor through variable gearing whereby the speed ratio of said driver motors may be varied.

12. Mixing apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources including a variable'speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including independent electrical driving connections for each, each such driving connection comprising a rotary receiver motor on the conveyor and an interconnected remote rotary driver motor, mechanism for driving said driver motors from a common variable speed rotary motor through variable gearing whereby the speed ratio of said driver motors may be varied, and means adjacent said last named mechanism for measuring the speeds of said driver motors.

13. Mixing apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources including a variable speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including independent electrical driving connections for each, each such driving connection comprising a rotary receiver motor on the conveyor and an interconnected remote rotary driver motor, mechanism for driving said driver motors from a common rotary motor through variable gearing whereby the speed ratio of said driver motors may be varied, and means adjacent said last named mechanism for measuring the speeds of said driver motors.

14. Mixing apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources including a variable speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including means for driving said conveyors at a variable ratio and variable speeds with a fixed ratio including a rotary motor common to said conveyors and at least one variable ratio drive between said motor and one of said conveyors.

l5. Mixing apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources including a variable speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including means for driving said conveyors at a variable ratio including a rotary motor common to said conveyors and at least one variable ratio drive between said motor and one of said conveyors.

16. Mixing apparatus comprising a material receiver, means forfeeding material thereto from a plurality of sources including a variable speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including means for driving said conveyors at a variable ratio including a rotary motor common to said conveyors and at least one variable ratio drive between said motor and one of said conveyors, and means for determining said speed ratio and the speed of at least one of said conveyors.

1'7. Mixing apparatus comprising a material receiver, means for feeding material thereto from a plurality of sources including a variable speed conveyor associated with each source, and means for varying the speed ratio of the conveyors including means for driving said conveyors at a variable ratio including a rotary motor common to said conveyors and at least one variable ratio drive between said motor and one of said conveyors, and means for determining said speed ratio.

JAMES A. FLINT. 

